The invention relates to a method of and apparatus for determining the sign or sign digit of the mutual temporal shift T of two similar stochastic signals.
Such signals arise, for example, in correlation speed meters (speedometers or tachometers) in which irregular properties of a surface are picked-up by two constantly spaced pick-ups moved relative to the surface. It is often desirable to ascertain simply the direction in which the movement is effected, without measuring the speed accurately.